STAFF had routinely been directed to pore over their chairman’s speeches and learn from them. One which Ye Jianming, the 40-year-old founder of CEFC, delivered last autumn—“Only One Step From Midsummer to Harsh Winter”—was a historical tale meant to motivate the troops. In it he compared his firm’s swift rise to that of Hu Xueyan, a 19th-century merchant banker. Hu amassed a fortune trading in salt, tea, arms and silk through close ties to China’s imperial elites, then fell from grace and went bankrupt.

Mr Ye did not mean the lesson to be pertinent to his own situation. CEFC was then enjoying its own midsummer. As China’s largest private oil group, it had just won a 14.2% stake in Russia’s state-backed oil firm, Rosneft, paying $9.1bn for one of the most significant shares of the world’s largest listed oil firm by production. Industry analysts outside China had been scrambling to study CEFC since early 2017 when it joined national oil...